A Magnetic Resonance Imaging (MRI), one of the medical diagnostic imaging devices, is a method that uses a Nuclear Magnetic Resonance (NMR) phenomenon to convert information of a test object, such as a living body, into an image. While a sufficient resolution is necessary in order to accurately interpret a target site in a clinical field, an MRI device, in principle, has a problem that a Signal to Noise Ratio (SNR) decreases when the resolution is increased. Therefore, in a general MRI device, the SNR is improved by increasing the Number of EXcitations (NEX) of signals, which is the number of multiple imaging and adding an identical site, that is, an identical position. A prior art of such image processing includes, for example, PLT 1. PLT 1 discloses correction processing of an image using Retinex theory that uses visual characteristics.